1. Field of the Invention
This invention relates to capping means and an ink jet printer using said capping means.
2. Related Background Art
Recently, it has been recognized that an ink jet recording apparatus is excellent in that it can perform high speed recording since noise during the recording is very small and it can be easily constructed as a high density multiple discharge port type ink jet printer. Further, it has been found that the ink jet printer has good color reproducibility for a color image. In general, an ink jet recording system (ink jet recording apparatus) is so constructed that ink droplets are caused to be discharged and fly from a discharge port of a recording head, and recording is carried out by their sticking on a recording sheet. So, in the ink jet recording apparatus, capping means for capping an ink discharging portion during non-recording is used to prevent the ink discharging portion from dryness and to prevent the ink discharging portion from contamination thereto.
Hereinafter, examples and related problems will be explained. A prior art ink jet recording head and capping means for capping a nozzle of the ink jet recording head are made of a flexible material such as rubber or the like. The capping means is provided with four raised wall portions which are the same in wall thickness and which contact the discharge port forming face of the recording head. Usually, when the ink jet printer does not perform its printing operation, the capping means is pushed with pressure onto the discharge port forming face side to make the discharge port airtight so as thereby to prevent it from dryness. At that time, the air sealing is carried out by the face contact of the edges of said four walls of the capping means with the periphery area of the discharge port forming face of the recording head.
On the other hand, a discharge port closing member is provided in the capping means in addition to the cap for the above function, which is pushed against the discharge port of the recording head to prevent ink from being discharged or flowing out from the discharge port during the capping mode of operation.
However, in the above-mentioned prior art, since the discharge port closing member and the cap are differently and independently operated as two parts, a gap is created between the cap and the nozzle closing member, which would obstruct the perfect airtight condition for the nozzle by the cap.
Further, two drive sources, one for moving the cap and the other for moving the nozzle closing member, are needed, which increases the manufacturing cost of the products.
Also, in the prior art, if after the engagement of the cap face with the ink jet head surface, it is intended that the pushing pressure of the cap against the ink jet head is further increased to tightly contact the entire cap face onto the head surface, then there would be produced a partial deformation or buckling of the four raised side portions of the cap, which decreases airtight quality. In that ease, supposing that airtightness were maintained, the deformation would be nonuniform, and thus, the pressure in the enclosed space defined by the ink jet head and the cap would not be constant, which would often lead to a destruction of a meniscus due to pressurized air into the nozzle.